- 期刊
- OpenAccess
有機物重金屬含量檢測－酸液選用對微波消化效果之影響
Effect of Acid Type on Closed-Vessel Microwave Digestion of Organic Matter
摘要
影響微波消化效果的因子甚多，分解時間、加熱溫度、壓力、酸液組合及樣品量等。本試驗以BCR060水生植物體（Lagarosiphon major）為標的，探討酸液選用對有機物微波消化效果之影響。硝酸是最常使用的分解試劑，因其可有效率地分解有機質且在原子光譜技術中最不易有分析干擾。惟對於某些難分解的物質，特別是含矽化合物，單以硝酸是無法完全將物質破壞的。試驗指出，以硝酸為主試劑時，添加雙氧水對樣品分解效果並不具提昇效應，而鹽酸的存在及添加四氟硼酸均可增加重金屬回收率。按試驗最終建議條件（6 ml之HNO3：HCl = 9：1混合酸液，0.05 ml四氟硼酸）分析，Cd、Cr、Cu、Ni、Pb和Zn回收率分別為108%、92%、92%、88%、91%和97%。
並列摘要
Various parameters (time of heating, temperature, pressure, composition and kinds of acids, sample mass, etc.) affect the digestion process. The closed-vessel microwave digestion of a certified reference materials BCR060 in nitric acid or in a mixture of nitric acid and other acids (hydrogen peroxide, hydrochloric acid and tetrafluoroboric acid) was studied. Nitric acid is the most widely used primary oxidant for the decomposition of organic matter due to its oxidative capacity and no severe analytical problems. However, nitric acid alone cannot dissolve all the material that present in the sample, thus leading to poor recoveries for many elements. The results show that hydrogen peroxide added into the mineralization procedure can not improve the recovery. The presence of hydrochloric acid can increase oxidative capacity, thus increasing the recovery. Mixtures of acids with tetrafluoroboric acid are particularly efficient in oxidative of organic matter. The recovery of heavy metals for BCR060 using 6 ml 9 : 1 of HNO3 : HCl mix acid and 0.05 ml HBF4 at 180℃ for 10 min were 108% for Cd, 92% for Cr, 92% for Cu, 88% for Ni, 91% for Pb and 97% for Zn.